Bleeding time factor

V.F. ) is intended to suggest that the effector might also be the von Willebrand factor or bleeding-time factor this feature of the model was proposed before it became apparent that factor VIII synthesis and the shortening of the bleeding time are mediated through distinct components. 

O. Egeberg has estimated factor VIII concentrations in a number of clinical conditions. Among those that may be loosely grouped together as chronic inflammatory, he has found an increase in factor VIII concentration in patients with atherosclerotic heart disease (E5), diabetes (E15), and miscellaneous chronic disorders (E3). In each study concomitant increases in factor VIII and fibrinogen were found, and in the second and third there was also some increase in factor V among the patients studied. An increase in the bleeding-time factor has been described in diabetes (02), in atherosclerotic disease (03) and in multiple myeloma (P6). 

In pregnancy, diabetes, and chronic inflammatory states there is a sustained rise in factor VIII concentration, accompanied by increases in other clotting factors, of which fibrinogen is the most constant and probably the most closely correlated quantitatively. In diabetes and atherosclerotic disease there is also an increase in the bleeding-time factor. Similar effects on the clotting factors can be produced by applying stresses which operate over a few days, such as the intramuscular injection of the subject s own blood. The rate of increase in factor VIII concentration indicated by serial assays is not more rapid than may be seen in patients with von Willebrand s disease after infusion of hemophilic plasma, and may therefore be reasonably ascribed to an increased rate of synthesis, since there is... 

Vitamin K is an essential factor in the production of coagulation proteins within the liver. Elevated clotting times from decreased protein synthesis are indistinguishable from those produced by low vitamin K levels caused by malnutrition or poor intestinal absorption. Vitamin K (phytonadione) 10 mg subcutaneously daily for 3 days can help to establish whether the prolonged bleeding time results from loss of synthetic function in the liver or vitamin K deficiency. 

Pharmacologic Therapy Treatments used to decrease bleeding time in patients with uremic bleeding include cryoprecipitate, which contains various components important in platelet aggregation and clotting, such as von Willebrand factor and fibrinogen. Cryoprecipitate decreases bleeding time within 1 hour in 50% of patients. However, cost and the risk of infection have limited the use of cryoprecipitate. 

Desmopressin (DDAVP) increases the release of factor VIII (von Willebrand factor) from endothelial tissue in the vessel wall. Bleeding time is promptly reduced, within 1 hour of administration, and is sustained for 4 to 8 hours.42 Doses used for uremic bleeding are 0.3 to 0.4 mcg/kg intravenously over 20 to 30 minutes, 0.3 mcg/kg subcutaneously, or 2 to 3 mcg/kg intranasally. Repeated doses can cause tachyphylaxis by... 

Hematologic von Willebrand disease Idiopathic thrombocytopenic purpura Factor VII defect causing impaired platelet adhesion and increased bleeding time Decrease in circulating platelets—can be acute or chronic... 

XIII Umbilical cord, intracranial, and joint bleeding recurrent miscarriages, impaired wound healing Normal PT, aPTT, thrombin time, bleeding time Specific factor XIII assay... 

Heparin inhibits reactions that lead to clotting, but does not significantly alter the concentration of the normal clotting factors of blood. Although clotting time is prolonged by full therapeutic doses, in most cases it is not measurably affected by low doses of heparin. Bleeding time is usually unaffected. 

Fondaparinux does not inactivate thrombin (activated Factor II) and has no known effect on platelet function, fibrinolytic activity, or bleeding time. 

Von Willebrand s disease Assess levels of factor VIII coagulant, factor VIII antigen, and ristocetin cofactor skin bleeding time may also be helpful... 

Mecfianism of Action A low-molecular-weight heparin that potentiates the action of antithrombin 111 and inactivates coagulation factor Xa. Therapeutic Effect Produces anticoagulation. Does not significantly influence bleeding time, PT, oraPTT. Pharmacokinetics ... 

Effect on blood Platelets are the important factors in thrombus formation and aspirin has been shown to inhibit platelet aggregation. They reduce the blood prothrombin level by inhibition of prothrombin synthesis and prothrombin time is prolonged. The aspirin suppresses the synthesis of thromboxane (TXA ) in the platelets. They also prolong the bleeding time due to prevention of platelet aggregation which may be due to inhibition of release of adenosine diphosphate (ADP) from the platelets by salicylates. 

In one second-generation recombinant factor VIII product, ReFacto , hemophilic dogs were used to demonstrate utility for bleeding time correction, association with von Willebrand s factor, and evaluating pharmacokinetics... 

Hara T, Yokoyama A, Tanabe K et al. (1995) DX-9065a, an orally active, specific inhibitor of factor Xa, inhibits thrombosis without affecting bleeding time in rats. Thromb Haemost 74 635-639... 

Sato K, Kawasaki T, Hisamichi N et al. (1998) Antithrombotic effects of YM-60828, a newly synthesized factor Xa inhibitor, in rat thrombosis models and its effects on bleeding time. Br J Pharmacol 123 92-96 Yamazaki M, Asakura H, Aoshima K et al. (1994) Effects of DX-9065a, an orally active, newly synthesized and specific inhibitor of factor Xa, against experimental disseminated intravascular coagulation in rats. Thromb Haemostasis 72 393-396... 

Brassard JA, Meyers KM (1991) Evaluation of the buccal bleeding time and platelet glass bead retention as assays of hemostasis in the dog the effects of acetylsalicylic acid, warfarin and von Willebrand factor deficiency. Thromb Haemost 65 191-195... 

Factor VIII levels strongly reduced due to defective protection by vWF highly prolonged bleeding time, hemorrhage, spontaneous bleeding mice useful for investigating the role of vWF delayed platelet adhesion in ferric-chloride-induced arteriolar injury (Denis et al. 1998 Ni et al. 2000). 

Superwarfarins lower the blood concentrations of the vitamin K-dependent clotting factors II, VII, IX and X this results in prolongation of prothrombin time (PT) and partial thromboplastin time (PTT). PT and PTT should be repeated at least twice daily until a normal PT and PTT are established. Also, the blood clotting time and the bleeding time should be measured. Blood is often demonstrable in the excreta. Secondary hypochromic or microcytic anemia may be marked (Goldfrank et al, 2002 Nelson et al, 2006). 

Gralnidc HR, Ride ME, Mckeown LP, Williams SB, Parker RI, Maisonneuve P, Jeanneau C, Sultan Y Platelet von Willdtrand factor An important determinant of the bleeding time in type I von Willebrand s disease. BIocxl68 58-61,1986. 

Mannucci PM, Moia M, Rebulla P, Altieri D, Monteagudo J, Castillo R Correction of the bleeding time in treated patients with severe von Willebrand disease is not solely dependent on the normal multimeric structure of plasma von Willebrand factor. Am J Hematol 25 55-65,1987. 

Cattaneo M, Moia M, DellaValle P, Castellana P, Mannucci PM DDAVP hortens the prolonged bleeding times of patients with severe von Willd)rand disease treated with oryopredpitates. Evidence for a mechanism of action independent of released von willebrand factor. Blood 74 1972-1975,1989. 

Hutton RA, Hales M, Kernoff PB. A study of the effect of ethamsylate (Dicynene) on the bleeding time, von Willebrand factor level and fibrinolysis in patients with von Willebrand s disease. Thromb Haemost 1988 60(3) 506-7. 

---